Polyamorphism of vapor-deposited amorphous selenium in response to light

Significance Amorphous selenium (a-Se) has a complicated molecular structure with overcoordinated defects and dangling bonds. This light-sensitive structure can undergo significant changes including bond breakage, reconnection, and defect formation upon illumination with above-bandgap light. Light sensitivity makes a-Se a unique system to study the role of surface structure and dynamics on stable glass formation during physical vapor deposition. We show that illumination during deposition produces less dense, more anisotropic, and kinetically more stable glasses, due to better network formation at the surface. This is a demonstration that light can be used to manipulate surface properties to generate distinct polyamorphic solid states that are not accessible through liquid quenching or aging.